Skylark: Improve documentation for configuration transitions.

--
MOS_MIGRATED_REVID=90061800
diff --git a/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java b/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java
index f173218..36444a3 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java
@@ -85,11 +85,11 @@
 
   //TODO(bazel-team): proper enum support
   @SkylarkBuiltin(name = "DATA_CFG", returnType = ConfigurationTransition.class,
-      doc = "The default runfiles collection state.")
+      doc = "Experimental. Specifies a transition to the data configuration.")
   private static final Object dataTransition = ConfigurationTransition.DATA;
 
   @SkylarkBuiltin(name = "HOST_CFG", returnType = ConfigurationTransition.class,
-      doc = "The default runfiles collection state.")
+      doc = "Specifies a transition to the host configuration.")
   private static final Object hostTransition = ConfigurationTransition.HOST;
 
   private static final LateBoundLabel<BuildConfiguration> RUN_UNDER =